In one method for a radio communication system such as a radio communication system involving cellular telephones and the like, the system includes base stations installed in high positions and mobile stations, a service area having a radius of about 1 km, for example, is allocated to one base station, and the base stations and the mobile stations communicate with each other.
However, radio waves hardly reach shielded locations due to straightness, and also are subjected to propagation attenuation, thereby creating out-of-service (so-called no service) areas. Installation of a repeater (also called a booster) is proposed as a technique for avoiding such a problem. FIG. 14 is a view showing a configuration example of a system including such a repeater station.
FIG. 14 is the view shown in Non-patent Document 1 cited below, in which a service area is secured by a repeater that receives a signal from a base station (AP) by an antenna ATA1 and emits radio waves from an antenna ATM1 for a mobile station MT to a mountain area which is out of service. While this example depicts the mountain area, installation of repeaters in an urban area having many areas behind buildings and the like has been considered as well in recent years, because the straightness of the radio waves is strengthened due to a shift of the band frequency available for radio communication to a higher frequency band (from a conventional band of 800 MHz to a band of 2 GHz or 4 GHz, for example). FIG. 15 illustrates views showing such an example, in which FIG. 15(a) shows a configuration without a repeater and FIG. 15(b) shows a configuration with a repeater. An area which the radio waves can hardly reach because of a building or the like (a weak electric field area behind a building) emerges in the case without a repeater. Accordingly, the electric field intensity of an area behind a building can be increased by installing a repeater for the area behind the building as shown in FIG. 15(b).